Digital radio, for example Digital Audio Broadcast (DAB) technology, enables large numbers of radio stations to be received terrestrially on special digital receiver systems. Along with the audio signal, data identifying the channel name, current presenter, song etc. is also broadcast so that it can be displayed on a display of the reader. The signal transmission is generally considered more robust as it does not suffer from the gradual fading experienced by analogue radio technologies.
In vehicle radio systems, there is currently a limited take-up of in-situ digital receivers for DAB. A limited number of new vehicles are provided with DAB as standard and, as an optional upgrade feature, the additional cost tends to deter take-up. For older cars, replacement of the original head unit tends to be expensive also, and inconvenient, requiring technical specialists.
Retro-fit solutions do exist but tend also to be inconvenient. One method is to attach a DAB antenna to the windscreen (in the manner of a stand-alone satellite navigation device) which is connected to a stand-alone control unit also connected to the windscreen or dashboard. Power is provided via the cigarette lighter socket to the control unit and transmission of the received DAB signal is via a FM transmitter to a selected free frequency manually tuned at the in-situ head unit, or plugged into an Aux-In port if one is available. In general, retrofit solutions require a special DAB aerial, dedicated control panel, and connection to the car's battery via the cigarette lighter or via the internal loom. In some cases, specialised installing is required, and overall the solutions tend to be fairly expensive and intrusive, involving additional wires and components to be stuck to the windscreen or dashboard.